According to a prior invention of mine, described in German Pat. Nos. 1,080,633 and 1,170,481 as well as German published specification No. 1,798,346, azimuthal and/or elevational data required for finding the direction of an incoming beam are determined with the aid of an antenna array comprising three loop antennas and three dipole antennas. The three loop antennas are located in mutually orthogonal planes whose intersections are in line with the dipoles. The analog voltages appearing on respective output terminals of these two sets of antennas are multiplied in various combinations and the resulting voltage products are algebraically combined to yield the desired data. For azimuth determination, four such multiplications will suffice; to find both the azimuth and the angle of elevation, six multiplications are needed.
For a correct evaluation of the intercepted radiation, the six channels carrying the output voltages of the three loop antennas and the three dipole antennas must be accurately calibrated so that their phase and attenuation characteristics are identical over the entire frequency range. Manual recalibrations, generally necessary before each measuring operation, are time-consuming and prevent the evaluation of incident signals of short duration. Circuitry for automatic recalibration is available but is rather complex and correspondingly expensive.